Container comprising an inner pouch

ABSTRACT

A container comprises a substantially dimensionally stable outer wall and an easily deformable inner pouch which gradually contracts upon discharge of the contents of the container. As a result, pressure compensation is provided in the increasing space between the outer wall and the inner pouch. The outer wall and the inner pouch have, therebetween, a layer of a pressure compensating material that expands when acted upon by an agent. The expanding layer comprises, in an exemplary embodiment, citric acid and sodium bicarbonate foam acting against the inner pouch. The foamed pressure-compensating layer supports the inner pouch so that no vacuum is generated in the pouch.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY

This application claims the benefit of and priority to PCT applicationno. PCT/DE00/01849, filed Jun. 7, 2000, the entire disclosure of whichis incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a container comprising a substantiallydimensionally stable outer wall and an easily deformable inner pouchinto which a pharmaceutical liquid can e.g. be filled that can bedischarged with a pump attached to the neck of the container. However,the contents of the container may also be a cream or a past which isdischarged from the opening of the container by compressing the outerwall.

The container may have the shape of a bottle or e.g. of a small tube,its shape being not limited in any way.

There are known containers consisting of a substantially dimensionallystable outer wall and an easily deformable inner pouch which areproduced, for example, in a coextrusion type blow molding process andconsist of two plastic layers that do not establish any connection witheach other, i.e., the inner pouch which has first been inflated incontact with the dimensionally stable outer wall of the containerdetaches from the outer wall when the contents of the container aregradually discharged.

To enable the inner pouch to contract in accordance with the dischargedvolume, some kind of pressure compensation must take place between theouter wall of the container and the contracting inner pouch. To thisend, pressure compensating holes through which air can enter into thespace between the outer wall and the inner pouch are formed in the outerwall in the formerly known containers of the type in question.

Although a pressure compensation takes place through the holes in theouter wall, a negative pressure is often created in the inner pouchbecause a complete pressure compensation along the whole outercircumference of the inner pouch does not always take place andrestoring forces are created by the contraction of the inner pouch, withthe result that the inner pouch tries to return to its natural form to acertain extent.

The negative pressure prevailing in the inner pouch has, in turn, theconsequence that air can enter into the inner pouch, either through fineopening in the wall of the inner pouch or, for example, due to leakagein the area of a possibly existing pump.

The entry of air into the inner pouch is highly undesired because thismay deteriorate the quality of the contents of the container and becausethe liquid level in the inner pouch may fall to such an extent that partof the contents of the container can no longer be discharged, forinstance because of the fact that the liquid level falls below the inletopening of the suction tube of a pump.

BRIEF SUMMARY OF THE INVENTION

It is the object of the present invention to develop a container of thetype in question in such a manner that pressure compensation takes placein a more advantageous way between the inner pouch which contracts upondischarge of the contents of the container and the substantiallydimensionally stable outer wall.

In accordance with the present invention, the outer wall of thecontainer and the inner pouch have arranged thereinbetween an expandablematerial which, upon discharge of filling material from the inner pouch,fills the increasing space between the outer wall and the inner pouch.

Preferably, the expandable material is positioned along substantiallythe whole space between the inner pouch and the outer wall, but it isalso within the scope of the invention that the expandable material mayonly be disposed in some portions.

The outer wall and the inner pouch may be firmly connected to each otherat individual places, which is preferably the case in the bottom area ofthe container, so that the inner pouch does not contract in axialdirection, but definitely contracts in radial direction, which is ofadvantage to a complete discharge of the contents of the container.Suitably, outer wall and inner pouch are also firmly interconnected inthe area of the container opening, i.e. e.g. on a container neck, sothat an outwardly tight inner space is created between the outer walland the inner pouch.

In a further development of the invention, the expandable materialpasses at least in part into a foam-like state upon the action of anagent. The foam-like expandable material fills the space created betweenthe inner pouch and the outer wall upon the discharge of the contents ofthe container's inner pouch and the accompanying contraction of theinner pouch and the expandable material supports the inner pouch so thatany negative pressure that might cause the entry of air into the innerpouch can virtually no longer be generated in the pouch.

As a rule, it is also possible that the expandable material graduallypasses in part into an unfoamed, purely gaseous state upon the action ofa suitable agent, thereby filling the space between outer wall and innerpouch. In such a case said space must be sealed hermetically to theoutside.

In a further development of the invention, the agent which makes thepressure compensating material expand may be a substance which comesinto contact with the expandable material.

The agent/substance may be water or water vapor which induces a pressurecompensating layer to foam or expand if the layer (preferably) comprisescitric acid and sodium bicarbonate. This is an advantageous developmentof the invention, and it should here be explicitly pointed out that saiddevelopment is not limited to the indicated expandable material and thesubstance water or water vapor which causes the foaming process.

When water vapor is used as and agent for expanding the intermediatelayer between outer wall and inner pouch, the water vapor preferablypasses through the inner pouch according to a further proposal of theinvention. To this end, the inner pouch consists of a material which ispermeable to water vapor to a predetermined degree. For instance, veryfine pores may be provided which, although they are permeable to watervapor, are not permeable to the remaining components of the contents ofthe container.

The agent for initiating the expansion of the pressure compensatinglayer can also act form the outside on the container or can beintroduced through the outer wall into the intermediate space. Onepossible example is that that UV radiation impinges through the outerwall of the expandable material. Such UV radiation can, e.g., take placeat a radiation station provided for said purpose after the container hasbeen filled, and lead to an expansion in the intermediate space, and anegative pressure may be generated there by the contracting pouch.

As for the method of producing the container according to the invention,there are no restrictions. For instance, the container can be producedin a coextrusion type blow molding process from three layers—one layerfor the inner pouch, one intermediate layer of expandable material, andone layer for the outer wall. The outer wall and the inner pouch canalso be produced separately, the expandable material being applicable asa layer to the inner pouch or internally to the outer container. It isalso not necessary that the outer container consists of plastics. Ametal sheet may e.g. also be used as the material for the outercontainer.

The invention shall be described in more detail with reference to anembodiment shown in the drawings in which like numerals identify likecomponents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical section through a container, in accordance with thepresent invention;

FIG. 2 is a bottom view of the container of FIG. 1, in accordance withthe present invention;

FIG. 3 is a side view of the container of FIGS. 1 and 2, in accordancewith the present invention; and

FIG. 4 is a top view on the container of FIGS. 1–3, in accordance withthe present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The container shown in the FIGS. 1–4 is produced in a coextrusion typeblow molding process from a three-layered tubular blank. The outer layer1 consists of a relatively rigid plastic material so that said outerwall of the container substantially maintains its dimensional stabilityeven if the contents of the container are discharged. The intermediatelayer 2 comprises a mixture of citric acid and sodium bicarbonate, whilethe inner pouch 3 consists of a non-rigid plastic material.

On the bottom, as shown in FIGS. 1 and 2, the mold cavity of the blowmold is designed such that when the blow mold is closed a pinch-off seam4 of a substantially diamond-shaped cross section is created in whichinner pouch 3 is clamped, as shown, partially, in FIG. 1. The squeezingin of inner pouch 3 has the effect that inner pouch 3 cannot contract inaxial direction

In the area of the opening 5 of the container, two vent beads 6 areformed in the outer wall 1. The vent beads prevent air from beingentrapped during mounting of a bottom part of the pump. Vent beads 6 donot communicate with the space between the outer wall 1 and the innerpouch 3.

The container is intended to receive a substance which contains water.The inner pouch 3 is permeable to water vapor to a predetermined degree,the water vapor initiating the expansion of layer 2 after having passedthrough the wall of the inner pouch. A material foam is gradually formedbetween the wall 1 and the inner pouch 3, the foam filling the spacebetween the two layers upon discharge of the filling substance, therebysupporting the inner pouch 3 in such a way that no negative pressure canbe generated therein.

As noted above, the agent for initiating the expansion of the pressurecompensating layer 2 can also act from the outside of the container orcan be introduced through the outer wall 1 into the intermediate space.One possible example is that that UV radiation 7 impinges through outerwall 1 of the expandable material. Such UV radiation can, e.g., takeplace at a radiation station (not shown) provided for that purpose afterthe container inner pouch 3 has been filled, and lead to an expansion inthe intermediate space, and a negative pressure may be generated thereby the contracting pouch 3.

As for the method of producing the container according to the invention,there are no restrictions. For instance, as noted above, the containercan be produced in a coextrusion type blow molding process from threelayers—one layer for the inner pouch 3, one intermediate layer ofexpandable material 2, and one layer for the outer wall 1. The outerwall 1 and the inner pouch 3 can also be produced separately, theexpandable material 2 being applicable as a layer to the inner pouch 3or internally to the outer container 1. It is also not necessary thatthe outer container 1 consists of a plastic. A metal sheet may, forexample, also be used as the material for the outer container 1.

This description is exemplary and is not intended to be limiting, sincepersons of skill in the art will recognize other embodiments fallingwithin the scope of the present invention, as set forth in the followingclaims

1. A container comprising a substantially dimensionally stable outerwall and an easily deformable inner pouch, including an expandablematerial which, upon action of an agent gradually passes into afoam-like or gaseous state and fills the space created between saidinner pouch and said outer wall upon discharge of filing material fromsaid inner pouch, characterized in that said expandable material (2) isarranged between said outer wall (1) and said inner pouch (3), and thatsaid agent passes through the wall of said inner pouch or thedimensionally stable outer wall to said expandable material (2); andwherein said filing material is not mixed with said expandable material.2. The container according to claim 1, characterized in that upon actionof said agent, said expandable material passes at least in part into afoam-like state.
 3. The container according to claim 1, characterized inthat said agent is a substance which comes into contact with saidexpandable material.
 4. The container according to claim 3,characterized in that said substance is water vapor or water.
 5. Thecontainer according to claim 1, characterized in that said expandablematerial comprises citric acid and sodium bicarbonate.
 6. The containeraccording claim 1, characterized in that said inner pouch consists of amaterial which is permeable to water vapor to a predetermined degree. 7.The container according to claim 1, characterized in that said containeris produced in a coextrusion type blow molding process.
 8. The containeraccording to claim 1, characterized in that expandable material isapplied as a layer to said inner pouch or internally to said wall ofsaid container.